We propose continuation of a Center for In Vivo Microscopy, a National Center for Research Resources dedicated to the development of magnetic resonance microscopy (MRM) and the application to biomedical research. Five key technical developments have been targeted to advance the state of the art: A) hyperpolarized (HP) gas for MRM in the lung and vasculature using generalized projection encoding, B) the stable animal platform to quantitate and minimize motion, C) high-temperature superconducting receivers for in vivo MRM, D) tools for diffusion tensor MRM, and E) techniques for neurohistology in transgenic mouse models. Eleven collaborative projects from diverse institutions are proposed: a) use of HP gas for studies in turbulence (Duke), b) extension of HP imaging strategies to patients with COPD (UVA), c) optimized strategies for HP imaging (Princeton), d) MR histology in 3D modeling of myocardium (Duke), mechanisms of acoustic perception (UNC-CH), e) MRM in environmental lung disease (Duke), f) MR histology of neurotoxins (FDA), g) medical application of the free electron laser (Duke), h) in vivo histology of fibrous capsule growth (CWU), i) the multidimensional human embryo (Duke), and j) MRM of gene delivery (Harvard). Four service projects are included exploiting the power of MR histology. An aggressive education, training, and dissemination program is included, utilizing new media (CDs, video, and the Next Generation Internet).